BlueEFFICIENCY from Mercedes-Benz stands for pioneering efficiency technologies as well as innovative packages of measures based on optimising fuel consumption and emission levels.

The BlueEFFICIENCY measures are comprehensive vehicle optimisations which save fuel and ease the burden on the environment. The R-Class also combines the most efficient engines with the optimum aerodynamics and energy management measures available to keep fuel consumption to a minimum.
For example, these:

The latest-generation CDI diesel engines display compelling performance characteristics coupled with low consumption levels. Injection pressure has been increased, smoothness of operation enhanced and noise levels optimised, while reduced compression makes for lower emission levels.